Effect of Mixed State on Suicidal Behavior in Patients With Bipolar Disorder

A history of mixed states was associated with an increased risk for suicidal behavior and more time in a depressive state.

The depressive component of mixed states in patients with bipolar disorder was found to be associated with a high risk for suicidal behavior, according to recent research published in Bipolar Disorders.

Researchers prospectively followed 429 participants with bipolar disorder for an average follow-up of 18 years (mean age, 36 years; 58% female; 66.2% with bipolar I disorder). Depressive or manic/hypomanic onset and severity were evaluated weekly with the Longitudinal Interval Follow-up and Evaluation. Suicidal behavior was defined as suicide completion or suicide attempt.

Mixed states were noted in 38.0% of participants, primarily those with bipolar I disorder. A history of mixed states was associated with an increased risk for suicidal behavior and more time in a depressive state. A total of 71.1% of the increased risk for suicidal behavior in patients with a history of mixed state could be attributed to the depression component of the disorder.

Risk for suicidal behavior increased during mania (hazard ratio [HR], 1.96; 95% CI, 1.28-2.99; P =.0019) and depression (HR, 5.49; 95% CI, 4.01-7.51; P <.0001) in bipolar I disorder. Risk was only increased during episodes of depression for bipolar II disorder (HR, 3.66; 95% CI, 2.51-5.35; P <.001). The effect of mixed states on suicidal behavior was less than additive for bipolar I and additive for bipolar II. According to the authors, this indicated that mixed state does not increase the risk for suicidal behavior beyond the risk associated with the depressive component.

The study authors concluded that "the takeaway message from this research is that much of the suicide risk related to having a history of mixed states is not a product of the mixed state itself, but rather can be attributed to a depression-predominant course of illness."